Kweku Adoboli, the 31-year-old trader charged with fraud over the $2 billion loss at UBS, allegedly began rogue trading back in 2008 - the height of the financial crisis - and may not have acted alone.

A tearful Kweku Adoboli went before magistrates this week and was charged with false accounting and fraud dating back back to October 2008.

The Telegraph reported that police were still uncertain whether they had uncovered the full extent of the alleged $2 billion fraud. Authorities are also investigating whether other people at the Swiss investment bank UBS may have been involved, according to The Telegraph.

It has been reported that UBS's internal controls were unaware of the massive loss allegedly caused by Kweku Adoboli.

According to the BBC, on Wednesday Kweku Adoboli told UBS that he had engaged in unauthorised trades, in his role as part of UBS's so-called Delta One trading team. The team deals in exchange traded funds. UBS then performed an examination of his trading positions and informed the Financial Services Authority and the police.

Kweku Adoboli was arrested on Thursday.

The company' has strict monitoring procedures designed to pick up improper conduct. However, those procedures seemed to have failed to detect what was happening. It raises the likelihood that the UBS' losses could have been even greater. It add to concerns that investment banks may not be fully capable of controlling the huge risks their traders take.

Kweku Adoboli's father John Adoboli, 63, told The Wall Street Journal that his son lived a frugal life, noting that his osn refused a suggestion at one time to buy a car because he didn't want to pay for parking.

"We are not flamboyant," John Adoboli said. "That is not how we are. We are simple people."